Medical valve with positive flow characteristics

ABSTRACT

A valve for selectively permitting a fluid flow between first and second medical implements is disclosed. The valve has a housing with an interface suitable for receiving a connector portion of a first medical device such as a catheter, and a seal made of a flexible material. The seal has a first end in fluid communication with the interface, a second end suitable for receiving the second medical device, and at least one slit in fluid communication with the first end and the second end. The slit defines a restricted fluid flow path and a relatively small interior volume when in an undisturbed state, defines an expanded fluid flow path and a larger interior volume upon the introduction of the second medical instrument into the slit, and retracts to define a restricted flow path and a small interior volume upon the withdrawal of the second medical device from the seal.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/636,163, filed Aug. 7, 2003, pending, which is a continuation of U.S.patent application Ser. No. 09/614,001, filed Jul. 11, 2000, now U.S.Pat. No. 6,695,817.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a medical valve, and in particularto a valve which, when connected between a first medical device, such asa fluid source, and a second medical device, such as a catheter,facilitates fluid flow therebetween, and when the first medical deviceis disconnected therefrom, induces a positive flow of fluid through thevalve in the direction of the second medical device.

2. Description of the Related Art

The manipulation of fluids for parenteral administration in hospitalsand medical settings routinely involves the use of connectors and valvesfor selectively facilitating the movement of fluids between two points.These valves are typically placed along a fluid flow line leading to apatient or other destination. For example, the tube may lead to acatheter having its tip positioned within a patient.

The valve is arranged so that a fluid source or other line may beconnected thereto for providing a fluid flow from the source to thepatient. When the fluid source or line is removed, the valve closes,sealing the line leading to the patient.

The element which is connected to the valve may comprise a tube or othermedical device such as a conduit, syringe, IV set (both peripheral andcentral lines), piggyback line, or similar component which is adaptedfor connection to the medical valve. Unfortunately, prior art valvessuffer from a problem arising from the disconnection of these medicaldevices from the valve.

These valves define a space within them through which a fluid or othermaterial may flow from the device to the line on which the valve ismounted. When the medical device is connected to the valve, it typicallyoccupies a portion of this internal valve space, displacing the fluid(whether it be a liquid or air) within the valve.

A problem arises when the medical device is disconnected from the valve.When the device is disconnected, it no longer occupies a portion of thespace in the valve. The increase in space within the valve causes thefluid in the valve and line to which the valve is connected, to move tofill the space. In effect, the removal of the device creates a suctionforce which draws fluid into the valve.

In the medical setting, this movement of fluid is very undesirable. Whenthe valve is connected to a fluid line leading to a patient, themovement of fluid through the line towards the space in the valve hasthe effect of drawing blood from the patient in the direction of thevalve. A serious problem may result in that this blood may clot and clogthe catheter near its tip, rendering it inoperable, and may even resultin a clot of blood in the patient, which may prove fatal.

One attempt at overcoming this clogging problem has been to coat theinner surface of the catheter near its tip in order to prevent bloodfrom sticking to its interior surfaces. This method has generally beenunsuccessful in preventing clogging of the catheter.

The risk of blood clogging of the catheter is significantly heightenedwhere the inner diameter of the catheter is small (e.g., 27 gauge).These small catheters have the advantage, however, in that they reducethe trauma and discomfort caused by insertion into a patient. Becausethese catheters have a very small passage therethrough, even a smallsuction force may draw sufficient amount of fluid back through acatheter toward the valve to introduce blood into the catheter tip,which blood may clog the catheter's passage.

Overcoming the above-stated problem is made more difficult whenconsidering other criteria which the valve must satisfy. For example,the valve should be arranged to so that it does not have any fluidstagnation points. If the fluid is allowed to stagnate in one or moreareas of the valve, bacteria growth and other problems may occur.

In addition, the valve should have an internal flow path which issmooth. Sharp edges and corners may damage blood cells and causehemolysis.

A valve that overcomes the above-stated problems is desired.

SUMMARY OF THE INVENTION

In accordance with one preferred embodiment, a medical valve forselectively permitting fluid to flow between a first medical device anda second medical device comprises a housing that has an interfacesuitable for receiving a connector portion of the first medical device,and a seal. The seal is made of a flexible material and has a downstreamend in fluid communication with the interface, an upstream end suitablefor receiving the second medical device, and a normally substantiallyclosed passage in fluid communication with the downstream end and theupstream end. The passage has a relatively small interior volume when inan undisturbed state and a larger interior volume upon the introductionof the second medical instrument into the upstream end of the passage.The passage retracts to define a restricted flow path and a relativelysmall interior volume upon the withdrawal of the second medical devicefrom the seal (the upstream end initially being sealed as the secondmedical device is withdrawn) so that a fluid occupying the interiorvolume is forced toward the downstream end as the passage wallscollapse.

In accordance with another preferred embodiment there is provided avalve seal for use in a medical valve having an interface for fluidcommunication with a first medical device. The seal comprises a firstend in fluid communication with the interface, a second end suitable forreceiving a second medical device, and at least one slit in fluidcommunication with the first end and the second end. The slit defines arestricted fluid flow path and a relatively small interior volume whenin an undisturbed state, and defines an expanded fluid flow path and alarger interior volume upon the introduction of the second medicaldevice into the slit. The slit retracts to define a restricted flow pathand a relatively small interior volume upon the withdrawal of the secondmedical device from the seal.

In accordance with another preferred embodiment a method is provided forcausing a positive flow in the direction of a first medical device froma valve that connects the first medical device to a second medicaldevice and has an associated seal. The seal is adapted to receive atleast a portion of the second medical device and provide fluidcommunication between the first and second medical devices. The methodcomprises the steps of withdrawing the second medical device from theseal and

-   -   permitting the seal to retract from a large interior volume to a        relatively small interior volume so as to displace any fluid        within the seal in the direction of the first medical device.

In accordance with another preferred embodiment there is provided amethod of preventing blood from flowing out of a patient into a catheterwhen a syringe is withdrawn from a valve between the syringe and thecatheter. The method comprises the steps of connecting the downstreamend of the valve to the catheter and inserting the end of the syringeinto a slit forming the upstream end of a normally substantially closedseal passage that is located in a resilient seal and is in fluidcommunication with the downstream end of the valve. This causes the sealpassage to open while providing sealing contact between the syringe andthe upstream end of the seal passage. The method further comprises thesteps of injecting fluid from the syringe through the seal passage tothe catheter and into the patient, and withdrawing the syringe, allowingthe walls of the seal passage to return to their substantially closedposition while initially maintaining sealing contact between theupstream end and the syringe. This provides a force urging fluid in thepassage toward the catheter.

In accordance with another preferred embodiment there is provided amedical valve for selectively permitting fluid to flow between a firstmedical device and a second medical device through an associated seal.The valve comprises an interface suitable for receiving a connectorportion of the first medical device, and a seal holder in fluidcommunication with the interface.

In accordance with another preferred embodiment a system foradministering fluid to a blood vessel of a patient comprises a catheterhaving an upstream end and a downstream end that is suitable forplacement in fluid communication with the blood vessel, and a syringesuitable for expelling fluid into the catheter. The system furthercomprises a valve having a fitting suitable for connection to theupstream end of the catheter and providing selective fluid communicationbetween the syringe and the catheter. The valve further comprises a sealmade of a flexible material. The seal has a downstream end in fluidcommunication with the fitting, an upstream end suitable for receivingthe syringe, and a normally substantially closed passage in fluidcommunication with the downstream end and the upstream end. The passagehas a relatively small interior volume when in an undisturbed state anda larger interior volume upon the introduction of the syringe into theupstream end of the passage. The passage retracts to define a restrictedflow path and a relatively small interior volume upon the withdrawal ofthe second medical device from the seal (the upstream end initiallybeing sealed as the syringe is withdrawn), so that a fluid occupying theinterior volume is forced toward the downstream end as the passage wallscollapse.

In accordance with another preferred embodiment there is provided amethod of making a medical valve seal of the type having a body made ofa flexible material and at least one slit formed within the body betweenadjacent first and second slit walls. The method comprises molding firstand second preforms, each preform comprising one of the first and secondslit walls and a perimeter edge portion, and pressing the first andsecond preforms together so that the first and second slit walls faceeach other. The method further comprises molding an additional amount ofa flexible material to at least part of the perimeter edge portions ofthe first and second preforms so that the first and second preforms andthe additional material form a unitary mass with the slit formedtherein.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught herein without necessarilyachieving other objects or advantages as may be taught or suggestedherein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments of the presentinvention will become readily apparent to those skilled in the art fromthe following detailed description of the preferred embodiments havingreference to the attached figures, the invention not being limited toany particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus summarized the general nature of the invention and itsessential features and advantages, certain preferred embodiments andmodifications thereof will become apparent to those skilled in the artfrom the detailed description herein having reference to the figuresthat follow, of which:

FIG. 1 is a schematic view of the use of a valve in accordance with theinvention to interconnect a catheter with a fluid source such a syringe;

FIG. 2 is a perspective view of the valve;

FIG. 3 is a front elevation view of the valve;

FIG. 4 is a side elevation view of the valve;

FIG. 5 is a perspective view of a seal for use in the valve;

FIG. 6A is a front elevation view of the seal;

FIG. 6B is a front cross-sectional view of the seal;

FIG. 7A is a side elevation view of the seal;

FIG. 7B is a side cross-sectional view of the seal;

FIG. 8A is a front elevation view of the seal;

FIGS. 8B-8D are cross-sectional schematic views of the insertion of amedical device into the seal taken through lines 8B-8B, 8C-8C and 8D-8Dof FIG. 8A, respectively;

FIG. 9 is a front cross-sectional view of a housing for use in thevalve;

FIG. 10 is a side cross-sectional view of the valve and the syringebefore insertion of the syringe into the valve;

FIG. 11 is a side cross-sectional view of the valve with the syringefully inserted;

FIG. 12 is a front cross-sectional view of the valve with the syringefully inserted;

FIG. 13 is a side cross-sectional view of the valve with the syringepartly withdrawn;

FIG. 14 a side cross-sectional view of the valve with the syringefurther withdrawn in comparison to FIG. 13;

FIG. 15 is a side elevation view of an alternative embodiment of thevalve, with the syringe partly inserted;

FIG. 16 is a side elevation view of an alternative embodiment of thevalve, with the syringe fully inserted;

FIG. 17 is a front elevation view of the valve as used with a syringehaving a Luer lock;

FIG. 18 is a side elevation view of an alternative embodiment of thevalve housing;

FIGS. 19A-19E are schematic views of a process of making the seal; and

FIG. 20 is a plan view of an overmold plate used in making the seal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-9 depict a valve 20 in accordance with a preferred embodiment ofthe invention. FIG. 1 illustrates a particular use of the valve 20 towhich it is well suited. Of course, the valve 20 may be used in avariety of other manners.

As illustrated in FIG. 1, the valve 20 may advantageously be used toselectively control the flow of fluid to a first medical device (such asa catheter 22 shown here) from a second medical device (generallycomprising a fluid source such as an ISO standard syringe 24). In thisarrangement, the catheter 22 is connected to one end of the valve 20 andhas a tip 26 inserted into the arm of a patient. The syringe 24 has acannula tip or Luer 28 that is inserted into the other end of the valve20, which is designed to accept the Luer 28 of the syringe 24 without aneedle installed on the Luer.

When so connected, the valve 20 permits fluid to flow from the syringe24 to the catheter 22 and into the patient. The valve 20 is alsoarranged so that when the syringe 24 is disconnected, fluid flow throughthe valve 20 is prevented. In addition, when the syringe 24 isdisconnected, the valve 20 generates a “positive” fluid flow, i.e. flowof fluid in the direction of the patient, thereby preventing blood fromentering the catheter 22 and causing the associated adverse effects.

FIGS. 2-4 depict one preferred embodiment of a valve 20 in accordancewith the invention. The valve 20 comprises a relatively rigid housing 30and a relatively flexible and resilient seal 32 disposed on or withinthe housing 30. The housing 30 has a Luer lock interface 34 at its lowerend to facilitate connecting the valve 20 to a variety of medicaldevices. One skilled in the art will readily appreciate that a number ofother interface or connection types are suitable for use in place of theLuer lock 34, such as a Luer slip connection or a barbed hose fitting.

The seal 32 has a slit opening 36 (best seen in FIG. 2) which isconfigured to permit the Luer 28 of a syringe 24 (see FIG. 1) to enterthe seal 32 upon application of moderate pressure by the user. Thesyringe Luer 28 thus enters a slit 38 (see FIG. 3) formed in theinterior of the seal 32. With the syringe Luer 28 thus inserted, theseal permits fluid ejected from the syringe 24 through the Luer 28 toflow through the slit 38 and Luer lock 34 and into the catheter 22 orother medical device attached to the Luer lock 34.

FIGS. 5-7B show the seal 32 removed from the housing for purposes ofclarity. The seal 32 has a body 40 which may take the form of a slabhaving a flat, generally rectangular shape. Like the entirety of theseal 32, the body 40 is preferably formed of molded, 50 durometersilicone rubber, or is alternatively formed of synthetic polyisoprene.At one end of the body 40 is formed a flat, generally rectangular neck42 and a generally circular transverse flange 44. The neck 42 issituated between first and second lateral extensions 43 a, 43 b whichhave shoulders 43 c, 43 d comprising those portions of the lateralextensions nearest the flange 44. The body 40, neck 42 and flange 44thus form an integral unit, inside of which is formed the (preferablysubstantially planar) slit 38. The slit 38 extends from the slit opening36 (best seen in FIG. 2) in the flange 44 to a lead lumen 46 formed inan end of the body 40 opposite the flange 44. The lead lumen 46 ispreferably substantially cylindrical and centered about an axis that issubstantially parallel to or collinear with the longitudinal axis of theseal. The slit 38 is preferably substantially planar and of virtually nothickness unless a Luer is connected. The slit 38 thus forms (in itsundisturbed state, i.e. when the syringe Luer 28 has not been insertedinto the seal 32) a highly restricted fluid flow path from the slitopening 36 to the lead lumen 46. As used herein in reference to a flowpath, “restricted” means a flow path that permits either no fluid, or aclinically negligible amount of fluid, to pass.

The preferred configuration of the slit 38 and lead lumen 46 is bestseen in FIGS. 6A-7B. The slit 38 has a body portion 48 within the body40 of the seal 32. Advantageously, the body portion 48 is a region ofmaximum width, preferably about 0.228″, of the slit 38. The slit 38tapers to a point or region 50 of minimum width, which is preferablylocated within the neck 42. Advantageously, at the region 50 of minimumwidth the slit 38 is preferably about 0.120″ wide. In other words, thewidth of the slit 38 in the body portion 48 is almost twice that of theregion 50 of minimum width. From the region 50 of minimum width the slit38 tapers outward to the slit opening 36, where it attains a preferredwidth of about 0.200″. This tapered configuration acts as lead-in forinsertion of the syringe Luer 28 into the slit 38. The slit 38 may alsohave beveled corners 52 at its lower end, opposite the neck 42. At itslower end the slit 38 connects to the lead lumen 46 to facilitate fluidcommunication between the slit 38 and the lead lumen 46. The lead lumen46 preferably has a lead-in chamfer 54 and a beveled transition 56 tothe slit 38. The preferred inside diameter of the lead lumen 46 is about0.040″.

In the side views of FIGS. 7A and 7B, it may be seen that the seal 32has a T-shaped cross section before installation in the housing 30, withthe flange 44 forming the cross portion of the “T”. Viewed from theside, the slit 38 is uniformly thin, i.e. of no or virtually nothickness, as it runs from the top of the seal 32 to the lead lumen 46.However, upon installation in the housing 30, the thickness of the slit38 (when viewed from the side) will vary somewhat as will be explainedin greater detail below.

FIGS. 8A-8D show the effects, in terms of sealing performance, of thevarying width of the slit 38 after introduction of a syringe Luer 28into the slit 38. (The syringe Luer 28 is not shown in FIG. 8A forpurposes of clarity.) FIG. 8B shows the arrangement of the slit 38 andthe syringe Luer 28 at the region 50 of minimum width, when the Luer 28has been fully inserted into the slit 38. Due to the relative narrownessof the slit 38 at the region 50, the slit 38 draws up againstsubstantially the entire perimeter of the syringe Luer 28 at thatlocation, creating a relatively tight perimeter seal between the slit 38and the Luer 28. In other words, the perimeter of the open slit 38 atthe region 50 is less than the circumference of the Luer 28.

FIGS. 8C and 8D show that where the slit 38 is wider (i.e., in the bodyportion 48 of the slit and the transition from the region 50) the slitno longer contacts the entire perimeter of the syringe Luer 28, leavinggaps 57 on one or both sides and the end of the Luer 28. In other words,the perimeter of the open slit in the body portion 48 is greater thanthe circumference of the Luer 28. As will be discussed in greater detailbelow, this arrangement of a slit-Luer seal near the top of the slit 38and a fluid-occupiable volume (in the form of the gaps 57) below theslit-Luer seal, promotes a positive-flow function for the valve 20 whenthe syringe Luer 28 is withdrawn.

FIGS. 3, 4, and 9 show a preferred configuration of the housing 30 andthe installation of the seal 32 therein. The housing 30 is preferablyformed of molded polycarbonate, or alternatively formed from anysuitable thermoplastic. The housing 30 has a seal holder 58 attached tothe Luer lock 34; the seal holder preferably has a cylindricalconfiguration, but may comprise any shape or construction sufficient tohold the seal 32 on or in the housing 30 without interfering withoperation of the valve 20. The seal holder has an axial opening 60opposite the Luer lock 34, and first and second side openings 62 a, 62 bwhich have first and second top edges 63 a, 63 b that comprise the edgesof the side openings nearest the axial opening 60. A lead cannula 64(best seen in FIG. 9) extends from the Luer lock 34 toward the axialopening 60 and contains an internal lumen 66 which is in fluidcommunication with a lumen 68 in the Luer lock 34. The lead cannula 64is preferably substantially cylindrical or frusto-conical in shape andcentered about an axis that is substantially parallel to or collinearwith the longitudinal axis of the housing 30. A pair of lugs 70 arepositioned on the end of the seal holder 58 near the axial opening 60,to permit a Luer lock or other threaded connection (not shown) tothreadably engage the housing 30 at the axial opening 60.

As best seen in FIGS. 3 and 4, most of the seal 32 is situated withinthe seal holder 58, with the first and second lateral extensions 43 a,43 b of the seal 32 protruding from the first and second side openings62 a, 62 b. The lead lumen 46 of the seal 32 is situated so that thelead cannula 64 extends at least partway into the lead lumen,facilitating fluid communication between the seal 32 and the Luer lock34. The flange 44 covers the axial opening 60 and contacts the adjacentedges of the opening. Preferably, the distance between the axial opening60 and the top edges 63 a, 63 b of the side openings 62 a, 62 b isslightly larger than the distance between the flange 44 and theshoulders 43 c, 43 d of the lateral extensions 43 a, 43 b. Thisarrangement results in the application of a tensile force or preload tothe seal 32 between the flange 44 and the lateral extensions 43 a, 43 b.The preload arises as the shoulders 43 c, 43 d bear against the topedges 63 a, 63 b and the flange 44 bears against the edges of the axialopening 60. The preload causes the flange 44 to assume a slightlybowl-shaped or concave configuration as the edges of the axial opening60 bear against the underside of the flange 44. The bowl-shaped flange44 thus serves as a lead-in for the insertion of the syringe Luer 28into the slit opening 36 (best seen in FIG. 2), and tends to pinchclosed the slit opening 36 and thus enhances the ability of the seal 32to prevent fluid flow. The preload also prevents buckling of the sealalong its longitudinal axis and maintains the sides of the slit 38 inclose proximity along their entire length. The preload thus promotes arelatively thin slit below the flange 44, which enhances the sealingperformance of the slit 38.

FIGS. 10-14 illustrate the function of the valve 20 as a syringe Luer 28is inserted into and withdrawn from the slit 38. FIG. 10 shows the valve20 prior to insertion of the syringe Luer 28; at this point the slit 38defines a substantially closed or highly restricted flow path throughthe seal 32, marked by a very thin (or substantially nonexistent) paththickness T_(min) between slit walls 72 a, 72 b. This thin ornonexistent path thickness T_(min) prevails along most or substantiallyall of the length of the slit 38 below the flange 44. This conditionrestricts fluid flow through the seal 32 so as to seal off the catheter22 (see FIG. 1) or other medical device connected to the Luer lock 34.At this point the slit 38 also defines a relatively small interiorvolume V_(min) within the seal 32, between the slit walls 72 a, 72 b.(As used herein in reference to an interior volume of the seal,“relatively small” means a volume that is either nonexistent orclinically negligible in size.) In this initial state, the seal 32 issituated upon the lead cannula 64 such that substantially none of thelead cannula 64 extends into the slit 38.

FIGS. 11 and 12 show the valve 20 after the syringe Luer 28 has beencompletely inserted into the slit 38. The seal 32 has also beenstretched or forced downward onto the lead cannula 64, at least part ofwhich penetrates into the slit 38 itself. At this point the slit 38defines an expanded flow path through the seal 32, in that the slitwalls 72 a, 72 b have spread to a path width T_(max). The seal 32 thuspermits fluid to flow between the syringe 24 and the catheter 22. Inaddition, the slit 38 now defines a larger or maximum interior volumeV_(max). V_(max) comprises the entire space between the slit walls 72 a,72 b less the volume taken up by the cannula (but not the internallumen) of the syringe Luer 28 and less that portion of the lead cannula64 which has penetrated into the slit 38. Accordingly, under pressureexerted via the syringe 24 an amount of fluid substantially equivalentto V_(max) now fills the slit 38 between the slit walls 72 a, 72 b. Thisis also shown as gaps 57 in FIGS. 8C and 8D.

FIGS. 13 and 14 show the function of the slit 38 as the syringe Luer 28is withdrawn from the valve 20. As the syringe Luer 28 and lead cannula64 exit the slit, the slit walls 72 a, 72 b retract to substantiallytheir original configuration to once again define a narrow path width(approaching T_(min)) between them. This retraction of the slit walls 72a, 72 b reduces the volume between the walls; that is, the internalvolume within the slit 38 is decreasing from V_(max). Thus the amount offluid within the slit must also decrease from V_(max). Accordingly, theretracting slit walls 72 a, 72 b displace the fluid from the slit 38 asthe syringe Luer 28 is withdrawn.

The fluid thus displaced cannot flow out of the slit 38 through the topof the seal 32. As detailed above with regard to FIGS. 8A-8B, the slit38 maintains a tight seal against the syringe Luer 28 at the region 50of minimum width as the syringe Luer 28 is withdrawn. In addition, thedisplaced fluid cannot flow into the interior of the syringe 24 at alltimes relevant to the use of the valve 20. Therefore, substantially allof the displaced fluid must exit the slit 38 through the lead cannula 64and Luer lock 34, resulting in positive flow from the valve 20 uponwithdrawal of the syringe Luer 28.

FIGS. 15-18 show variations on the valve 20 disclosed above, whichvariations may be desirable under certain operating conditions. Forexample, as seen in FIGS. 15 and 16 the housing 30 may have a break 74running vertically between the axial opening 60 and one or both of theside openings 62 a, 62 b. The break 74 permits the seal holder 58 tospread open as a Luer slip 28 (as opposed to a Luer lock 76 shown inFIG. 17) is inserted into the seal 32. This spreading action has beenfound to be advantageous for using the valve 20 with a Luer slip 28, asthe valve 20 becomes less likely to squeeze or pinch the Luer 28 out ofthe seal 32.

FIG. 18 shows an alternative configuration of the housing 30, with acurved or streamlined appearance in comparison to the housing disclosedabove. Both this type of housing or the type disclosed above, may havean external coating or layer of a relatively soft, pliant material suchas a thermoplastic elastomer to enhance operator comfort and to promotethe theme of a valve 20 that provides a connection without the use ofsharp, puncturing elements such as needles or blades.

FIGS. 19A-21 depict a preferred method of making the seal 32. First, apair of preforms 202 a, 202 b are molded between first and second moldpairs 204 a, 204 b and 206 a, 206 b respectively. Each preform 202 has agenerally planar portion 208 that, in the completed seal 32, forms awall of the slit 38 (see FIGS. 6A-7B). A flange portion 210 is alsointegrally molded into both preforms 202. The sides of the flangeportion 210 are preferably set back from the upper face of the planarportion 208, to provide a space for overmold material (discussed infurther detail below) to flow between and connect the flange portions210. The molding of the preforms 202 is accomplished using conventionaltechniques and equipment, preferably by injecting a thermoset materialinto the cavity formed between the mold pairs 204 a, 204 b and 206 a,206 b and heating the molds and/or material to the set temperature ofthe specific material used. Pressure may be applied as needed to preventmaterial from leaking between the halves of the mold.

After this initial molding step, the mold halves 204 a, 206 a, with thepreforms 202 a, 202 b still positioned in them, are pressed togetherwith an overmold plate 212 positioned between the mold halves, asdepicted in FIGS. 19B-19C. The overmold plate 212, best seen in FIG. 20(with the outline of the preforms 202 also shown in phantom), comprisesa generally planar plate body 214 with an overmold opening 216 cut intothe body 214. The overmold opening 216 has a plan perimeter thatconforms to the outer edges of the completed seal 32, and may include amandrel 218 that projects from the lower portion of the opening 216 andforms the lead lumen 46 (see FIGS. 6A-7B) during the overmold process,as will be discussed in greater detail below. The contacting faces ofthe mold halves 204 a, 206 a and the overmold plate 212 areadvantageously substantially planar. Thus the mold halves 204 a, 206 a,plate 212, and preforms 202 a, 202 b define a mold cavity or volume 220between the walls of the overmold opening 216 and the outer edges of thepreforms 202 a, 202 b, and between the faces of the mold halves 204 a,206 a.

With the mold apparatus (mold halves 204 a, 206 a and overmold plate212) arranged as shown in FIG. 19C, additional thermoset material isinjected into the mold apparatus to fill the mold cavity 220 and formthe remainder of the seal 32. Preferably, the additional material isinjected soon (i.e., a few seconds) after the preforms 202 are moldedand while they are still somewhat hot from the initial molding. Theadditional material injected into the mold cavity 220 bonds to the edgesof the preforms 202 and forms the edges of the slit 38 in the completedseal 32. In other words, the remainder of the seal is overmolded ontothe “sandwich” of preforms 202. Preferably, the preforms 202 are pressedtogether with sufficient force during the overmolding process to preventthe additional material from migrating between the contacting surfacesof the preforms 202. This preserves the patency of the slit 38 bypreventing the contacting faces of the preforms 202 from bonding to eachother during the overmold step.

The overmold plate 212 may be made with a thickness approximately thesame as that of the “sandwich” of preforms 202 a, 202 b to define a moldcavity 220 that, as described above, comprises the open space betweenthe walls of the overmold opening 216 and the outer edges of thepreforms 202 a, 202 b, and between the faces of the mold halves 204 a,206 a. This overmold opening thus also has a thickness approximatelyequal to that of the preform sandwich, and all or nearly all of theovermold material injected therein bonds only to the edges of thepreforms 202 a, 202 b. In an alternative embodiment, the overmold plate212 may have a thickness greater than the preform sandwich. Thisthicker, alternative overmold plate thereby defines a mold cavity thatalso includes open space that is created between the mold halves 204 a,206 a and the outer (i.e., facing away from the slit in the completedseal) faces of the preforms 202 a, 202 b. The mold halves 204 a, 206 aare preferably configured with projections, ridges, channels, gaps orthe like to create such space during this alternative overmold stepwhile pressing the preforms together as may be needed during theovermold. Accordingly, in this embodiment the overmold material bonds toboth the edges and to the outer faces of the preforms 202 a, 202 b. Inother words this alternative overmold step involves injecting theovermold material into a mold cavity that surrounds most or all of thepreform sandwich, rather than overmolding to the only the edges of thepreforms.

It is preferred that the material added in the overmold step is similarto that utilized in molding the preforms 202; however, in otherembodiments the preform material and the overmold material may comprisedifferent but nonetheless suitable materials for manufacturing the seal,as discussed above. Therefore as used herein “a flexible material”refers to any material selected from the class of suitable sealmaterials as disclosed.

After the overmolding is complete, the mold halves 204 a, 206 a areremoved from the seal plate 212, which now contains a substantiallycompleted seal 32, as seen in FIGS. 19D-19E. The completed seal 32 iseasily removed from the seal plate 212, and the seal thus formedcomprises, as discussed above, a unitary mass of molded material withthe slit arranged within it.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. Thus, it is intended that the scope of the present inventionherein disclosed should not be limited by the particular disclosedembodiments described above, but should be determined only by a fairreading of the claims that follow.

1. A medical valve for selectively permitting fluid to flow between afirst medical device and a second medical device, the valve comprising:a housing having an interface suitable for receiving a connector portionof the first medical device; and a seal made of a flexible material, theseal having a downstream end in fluid communication with the interface,an upstream end suitable for receiving at least a portion of the secondmedical device, and a normally substantially closed passage in fluidcommunication with the downstream end and the upstream end, the passagebeing relatively wide in the region of the upstream end and the passagebeing relatively narrow in the region of the downstream end, the passageadapted to have a relatively small interior volume when in anundisturbed state and a larger interior volume upon the introduction ofthe second medical device into the upstream end of the passage, thepassage adapted to retract to define a restricted flow path and arelatively small interior volume upon the withdrawal of the secondmedical device from the seal, the upstream end adapted to initially besubstantially sealed against the inserted portion of the second medicaldevice as the second medical device is withdrawn, so that a fluidoccupying the interior volume is forced toward the downstream end as thepassage walls collapse.
 2. The medical valve defined in claim 1, whereinthe seal comprises: a lead lumen formed in the downstream end of thebody and in fluid communication with the passage; a neck formed in theupstream region of the seal; and a transverse flange in the upstreamregion of the seal, the transverse flange having at least one opening influid communication with the passage.
 3. The medical valve of claim 2,wherein the lead lumen is centered on an axis substantially parallel toor collinear with a longitudinal axis of the seal.
 4. The medical valveof claim 2, wherein the seal comprises a substantially rectangular slabof flexible material and the neck is coplanar with the body.
 5. Themedical valve of claim 1, wherein the passage in the undisturbed statetapers inwardly from the upstream end to a region of minimum width. 6.The medical valve of claim 5, wherein the passage in the undisturbedstate tapers outwardly from the region of minimum width toward thedownstream end.
 7. The medical valve of claim 2, wherein the seal hasfirst and second lateral portions and the housing further comprises: aseal holder attached to the interface, the seal holder comprising ahollow cylindrical member that extends from the interface and has anaxial opening opposite the interface, and first and second sideopenings; a lead cannula attached to and in fluid communication with theinterface and extending from the interface toward the axial opening,wherein the seal is disposed within the seal holder such that the leadcannula extends at least partially into the lead lumen, the flangeextends across the axial opening, and the first and second lateralportions of the seal body extend into the first and second sideopenings.
 8. The medical valve of claim 7, wherein the lead cannula iscentered on an axis substantially parallel to or collinear with alongitudinal axis of the housing.
 9. The medical valve of claim 1,wherein a lead cannula attached to and in fluid communication with theinterface extends from the interface into the downstream end of theseal, an end of the lead cannula being disposed within the passage at alocation in the upstream direction from the furthest downstreamperiphery of the interior volume of the seal.
 10. The medical valve ofclaim 7, wherein the seal is adapted to move within the housing in thedownstream direction upon insertion of the second medical device and tomove within the housing in the upstream direction upon withdrawal of thesecond medical device.
 11. The medical valve of claim 10, wherein thelead lumen of the seal expands as the seal moves in the downstreamdirection and the lead cannula extends further into the interior of thepassage of the seal.